Packaging processes characterized in high productivity and standardization of the articles to be packaged have reached an high automation level, but in those cases where the variability of the articles is a predominant peculiarity of the process, the presence of the man still is necessary.
That is what happens, for instance, in packing-shipping processes by which one or more articles are put inside suitable containers and sent over to the packaging station, where an operator is in charge of manually inserting filling or protective packaging material into the containers, being said material usually crumpled paper, expanded loose-fill chips, air bags or pads, air bubbles film, polyurethane foam expanded in place or others.
In these processes the filling materials have merely the function of filling the void volume left inside the container and of avoiding the articles from moving within that, therefore these applications are known as “void filling” packaging processes.
Air bags, air pads and crumpled paper packaging technologies rely on the manual inserting of said materials, dispensed by special machines, into the containers. The operator evaluates the needed amount of materials directly during the inserting action; if too much material has been dispensed, then the operator simply takes it out of the container and keeps it available for the next one. If the operator puts the material not properly into the container, then the operator can simply take it out and use it again for next packages.
Loose fill chips are usually, but not necessary, stored in big bags approximately 1 cubic meter volume capacity hanging on a support frame above the packaging station. The operator takes care of discharging the loose fill chips down into the container by means of a manual actuated valve, of driving the stream of chips towards void areas and of dosing the proper amount of material. If an over-dosing or wrong dispensing should occur, the consequence is just some chips on the floor to be cleaned up. If an underestimated dosing should occur, the operator simply needs to dispense some more chips.
Packaging technology by means of polyurethane foam expanded in place, known as “foam-in-place” or “foam-in-bag”, provides undiscussed benefits, however it is much more sensitive than the previously mentioned technologies. Foam-in-place is to be understood as a generic term that includes all systems capable to produce PU foam in situ, therefore both automatic or semi-automatic bag machines and hand held machines. Foam-in-place bags technology consists in inserting plastic bags into the container, being inside the bags a chemical substance or mixture that expands and fills therefore the void volume available in the container, this way blocking the articles contained. This technology requires a foam precursors mixing machine with a bags forming device.
The operator estimates the volume and the shape of the void space within the container where the articles to be packaged are, then the operator sets the foam-in-place system for the dispensing of the most appropriate bag or bags.
Commonly set parameters are the lengths of the bags, being the width depending on the film roll installed on the equipment, and the bag filling percentage, that is relative to the maximum bag volume allowed by the set length of the bag. This estimating and setting methodology is the one mainly adopted by the foam-in-place systems manufacturers, providing the operator an easy process managing methodology: the intuitive comparison between the void volume within the container and the volume of the expanded foam. However, this approach is very approximate, and experienced and skilled operators only are able to obtain acceptable, but never optimal, performance.
An undersized bag, due to wrong length or filling percentage, leads to a not effective package or to a waste of material, the expanded bag being difficultly re-employable. A light over-sizing leads to a waste of material; an over sizing may likely lead to a bag breaking and therefore the foam spreads over the articles; the oversized bag may prevent flaps from being closed as well. In both situations it is necessary to replace the bag and the obvious consequence is a waste of foam and a lost of productivity.
The bags estimation is even more complicated due to “shape factors”: the foam expands within the container driven both by the void space geometry and by the film layers of the bag in which it is contained. Because of that, it is not enough the operator estimates the void volume value to be filled, but he has to consider its shape also in order to set the most suitable bag.
Besides void filling applications, the target of other packaging processes is articles protection.
Crumpled paper, air bags or air pads packaging technologies allow packaging by tentative: material can be added, taken out or moved from an area to a different one without any problem.
Although foam-in-place is the most effective protective-packaging technology, it is also the most sensitive from the application stand point because a recovery chance is not given: if the bag is not the proper one for the addressed location or if it has been inserted wrongly, since the foam expansion starts there will not be chances to modify the situation: it will be necessary to replace that bag with a new one.
An oversized bag may shift, while expanding, the articles from the original position towards the container side, alternatively it may deform the container side; wrong sized or badly inserted bags may break the film (foam flows out). On the other hand, undersized bags will compromise the protection performance.
Furthermore, the foam expands in radial direction tending to assume a spherical shape; that characteristic does not help at all reaching distant corners or expanding through narrow corridors. Some void space geometry can be filled only by using several bags put in critical positions. Process unknown parameters are therefore the types and the number of bags to be dispensed, and the proper disposition inside the container, with the target of both protecting the articles at the maximum extent and optimizing the amount of dispensed foam.
With regards to that, it is known, through publication WO2007121169, a packaging system which relies on the void volume measurement within a container containing articles.
The void volume measured value is transmitted to a machine that dispenses, accordingly to that void volume value, a proper amount of packaging material, crumpled paper in a preferred embodiment of the invention. Then the operator manually receives the paper and inserts it into the container, without being driven or instructed about the most effective disposition.
As previously explained, and mostly with reference to the foam-in-place systems, the value of the void volume to be filled is not enough to realize a good package; it is indeed necessary to determine and interpret the geometrical location of the articles inside the container or, which is the same, the geometrical distribution of the void volume in order to make the right decision about the most suitable dispensing and inserting of packaging material. Again with reference to the foam-in-place technology, several bags are often necessary, accurately inserted and filled with the necessary amount of foam, which is calculated to fill a specific fraction of the total void volume only. By knowing this information, the difficult decisional step the operator has to make, particularly critical in foam-in-place systems, is not any more necessary; then the process automation becomes possible by using automatic devices able to dispense and insert the packaging material, these devices being driven by the instructions generated automatically through the processing of the geometrical distribution data acquired.
Hence the object of this invention is to provide a packaging apparatus and method that are more economical and more reliable than those known in the state of the art.